Heretofore, personal computers and computer terminals have been suggested which use touch-sensitive displays as inter-active user-interfaces for both input and output of information (e.g., text and graphics). A touch sensitive display of this type generally has a conventional display screen provided with a transparent, generally flat touch-sensitive screen as a frontplate. Typically, the touch sensitive display is used in conjunction with application programs specifically designed to take advantage of this type of I/O device. In use, some such application programs can cause the display screens to display simulated, conventional-typewriter keyboards. The simulated keyboard is then available for entering data and commands for use or execution in the application program that generated the keyboard, but not in other application programs. In other words, the simulated keyboards are dedicated for use only in the specific applications in which they have been programmed.
In known simulated keyboards of this type, each key of the simulated keyboard is represented by a discretely-defined area bounded by a frame. In each key frame there appears an indicium of an alpha-numeric character, or a character representing punctuation, other symbol, or function. The simulated keyboard is visible through the touch-sensitive-screen overlaying the display.
For typing on the simulated keyboard, the user touches the touch-sensitive-screen on the displayed keys in the same fashion that a typist uses a conventional typewriter. The "touches" on the display cause the generation of coded electrical signals corresponding to the locations that are touched, and thereby representing the displayed characters (e.g., capital or lower case letters depending on whether the displayed shift key is touched) or functions selected by the user. The coded electrical signals then are processed by the computer in the same manner that it would process the electrical signals generated by a conventional keyboard input device.
Unfortunately, using the touch-sensitive display as a combination I/O device presents certain complications. For instance, when the simulated keyboard is "called up" and displayed on the screen, it may very well occupy the entire rastor or a substantial portion thereof. In order to accommodate such a simulated keyboard, either the normal output screen of that program must be removed from view in its entirety, or the window in which the simulated keyboard appears must be an overlay which replaces and, thereby, removes from view, a substantial portion of the program's normal output screen.
Clearly, this would not be suitable for running standard, commercially-available software packages such as data processing, spread sheets, or data-base management programs, even if such simulated keyboards were made available within these programs. If the simulated keyboard were positioned in the same place on the screen whenever it were displayed in such programs, the simulated keyboard, as often as not, would replace or cover the "active portion" of the software output screen. The active portion is the area of the screen into which the information being typed is to be entered. It is easy to understand that, if the user must enter data in such programs without the active portion of the software output screen being visible, data-entry accuracy and/or efficiency would suffer, to say the least.
Accordingly, simply incorporating a touch-sensitive simulated keyboard in such programs would result in geometric conflicts between the normal software output screen and the simulated keyboard window.
The above-referenced patent application, Ser. No. 421,242 discloses various novel solutions to the geometric conflicts problem, while providing a touch-sensitive simulated keyboard (e.g., a typewriter-type keyboard) which is a general-purpose, rather than application-dedicated, I/O device or tool. The simulated keyboard program remains resident in computer memory, and is controlled at the operating system level rather than the software application level. In other words, the control of the simulated keyboard image, including its position within the display raster, is the responsibility of the basic input/output services of the computer. In this way, the touch-sensitive keyboard is resident within the computer as a system utility and is independent of any specific application run on the computer. Therefore, it can be used at the discretion of the computer user at any time in conjunction with any application program run on the computer.
While the various teachings of that patent application substantially advance the art, further solutions to the geometric-conflict problem, as well as other drawbacks of using the disclosed input/output device are desired to enhance, e.g., its ease of use, versatility and breathe of capabilities.
In addition to the geometric conflict problem, another drawback of using a simulated keyboard displayed on a touch-sensitive display is its effect on typing efficiency. The generally flat display "feels" different from conventional keyboards, and this can result in (or amplify) keystroke variations that cause, for example, a key to be pressed longer than usual. As with conventional electronic keyboards, prolonged pressing of a key generally will cause the character corresponding to it to be repeated. (For example, keeping the "B" key depressed will cause multiple "B's" to appear on the display.) It would be desirable to provide a simple and effective way for a user to avoid such typographical errors from occurring.